An overview of link-level measurement techniques for wide-area wireless networks

By building wireless link-level measurement tools we hope to improvement the design, deployment and management of wide-area wireless community networks. This paper identifies existing link-level measurement techniques and discusses the advantages and disadvantages of each in the context of measuring and monitoring such networks. Finally, we make a case for the need for more sophisticated techniques and tools which will assist both day-to-day network operations as well as wireless network research

Wireless local area network planning: an overview

When planning a wireless local area network, there are design issues that need to be considered. In this paper, the fundamentals of planning a wireless local area network are introduced and discussed to highlight the requirements involved. Network constraints, as their relevance to wireless network design is investigated. The paper concludes with an overview of wireless network planning solutions including commercial and free software, and an introduction to the author’s research

Design of a processor to support the teaching of computer systems

Teaching computer systems, including computer architecture, assembly language programming and operating system implementation, is a challenging occupation. At the University of Waikato this is made doubly true because we require all computer science and information systems students study this material at second year. The challenges of teaching difficult material to a wide range of students have driven us to find ways of making the material more accessible. The corner stone of our strategy for delivering this material is the design and implementation of a custom CPU that meets the needs of teaching. This paper describes our motivation and these needs. We present the CPU and board design and describe the implementation of the CPU in an FPGA. The paper also includes some reflections on the use of a real CPU rather than a simulation environment. We conclude with a discussion of how the CPU can be used for advanced classes in computer architecture and a description of the current status of the project

Improving the performance of HTTP over high bandwidth-delay product circuits

As the WWW continues to grow, providing adequate bandwidth to countries remote from the geographic and topological center of the network, such as those in the Asia/Pacific, becomes more and more difficult. To meet the growing traffic needs of the Internet some Network Service Providers are deploying satellite connections. Through discrete event simulation of a real HTTP workload with differing international architectures this paper is able to give guidance on the architecture that should be deployed for long distance, high capacity Internet links. We show that a significant increase in the time taken to fetch HTTP requests can be expected when traffic is moved from a long distance international terrestrial link to a satellite link. We then show several modifications to the network architecture that can be used to greatly improve the performance of a satellite link. These modifications include the use of an asymmetric satellite link, the multiplexing of multiple HTTP requests onto a single TCP connection and the use of HTTP1.1

Magnetically warped discs in close binaries

We demonstrate that measurable vertical structure can be excited in the accretion disc of a close binary system by a dipolar magnetic field centred on the secondary star. We present the first high resolution hydrodynamic simulations to show the initial development of a uniform warp in a tidally truncated accretion disc. The warp precesses retrogradely with respect to the inertial frame. The amplitude depends on the phase of the warp with respect to the binary frame. A warped disc is the best available explanation for negative superhumps.Comment: 11 pages, 10 figures, MNRAS accepte

Superhumps: Confronting Theory with Observation

We review the theory and observations related to the ``superhump'' precession of eccentric accretion discs in close binary sytems. We agree with earlier work, although for different reasons, that the discrepancy between observation and dynamical theory implies that the effect of pressure in the disc cannot be neglected. We extend earlier work that investigates this effect to include the correct expression for the radius at which resonant orbits occur. Using analytic expressions for the accretion disc structure, we derive a relationship between the period excess and mass-ratio with the pressure effects included. This is compared to the observed data, recently derived results for detailed integration of the disc equations and the equivalent empirically derived relations and used to predict values for the mass ratio based on measured values of the period excess for 88 systems.Comment: 11 pages, 7 figures, 4 tables, accepted for publication in MNRA

Understanding veterinary leadership in practice

From early in employment, veterinary surgeons adopt a position of leadership, taking responsibility for case management, client communication and the coordination of the team of veterinary nurses and receptionists who facilitate their role. With time, many progress to become partners or directors within practice. A key ambition of the Vet Futures Report is ‘exceptional leadership,’ yet to date there has been little formal leadership training within the UK veterinary curriculums and a notable absence of veterinary-specific leadership literature.1 This vacuum in identifying the qualities of exceptional leadership raises the question of how the industry continues to progress, embracing the challenges of corporate ownership, growing numbers of veterinary surgeons and a turbulent macroenvironment during, and post, Brexit negotiations.2 Historically, leadership research has tended to follow a managerialist path,3 4 focusing analysis on alpha white men within US leadership.5–7 As such, ethnocentric leadership models pervade the literature. Critically, these models ignore contextual variation, the influence of leadership on the individuals within an industry and complexity.6 Therefore, in recent decades, literature has redirected to take a critical approach. In beginning to understand the value of leadership studies to the veterinary industry, the interconnection of leaders, followers, context and purpose in each unique leadership situation needs to be fully appreciated.8 Furthermore, to ensure exceptional leadership, we must first recognise its inseparability from the wellbeing of veterinary surgeons. Given the Vet Futures’ ambition of ‘exceptional leadership’ coupled with the paucity of literature on leadership in the veterinary industry, this study explores the experiences of leadership among senior veterinary surgeons (SVS), while acknowledging the complexity of multifactorial influence and uniqueness of practice. The value lies in reflecting on industry relevance.

The niche of benthic foraminifera, critical thresholds and proxies

Ecological studies of benthic foraminifera are carried out to explain patterns of distribution and the dynamics of communities. They are also used to provide data to establish proxy relationships with selected factors. According to niche theory, the patterns of distribution of benthic foraminifera are controlled by those environmental factors that have reached their critical thresholds. For each species, in variable environments, different factors may be limiting distributions both temporally and spatially. For a species or an assemblage to be useful as a proxy its abundance must show a strong correlation with the chosen factor. Since numerous factors influence each species, it is only in those environments where the majority of factors show little variation but one particular factor shows significant variation that the proxy relationship for that factor can be determined. On theoretical grounds, the reliability of using foraminiferal abundance as a proxy of a selected environmental factor should be restricted to the range close to the upper and lower thresholds. For oxygen, foraminifera are potential proxies for the lower limits but once oxygen levels rise to values of perhaps >1 or 2 ml l-1, there is no longer a relationship between oxygen levels and abundance. By contrast, the flux of organic matter over a large range shows a sufficiently close relationship with foraminiferal assemblages so that transfer functions can be derived for the deep sea. However, the relationship at species level is far less clear cut. Much more accurate estimates of primary productivity and modern organic flux rates are required to improve the determination of past flux rates

Patient reactions to a web-based cardiovascular risk calculator in type 2 diabetes: a qualitative study in primary care.

Use of risk calculators for specific diseases is increasing, with an underlying assumption that they promote risk reduction as users become better informed and motivated to take preventive action. Empirical data to support this are, however, sparse and contradictory